Synthesis and structure of 2-amino- 5-azolyl-3-cyano-4H-pyrans

Previously unknown 5-azolylpyrans were obtained by reactions ofN-acetonyl- andN-phenacylimidazoles, -triazoles, and -tetrazoles with arylmethylenemalononitriles. The structure of 2-amino-3-cyano-6-methyl-5-(5-nitrotetrazol-2-yl)-4-phenyl-4H-pyran was established by X-ray structural analysis.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2050–2055, August, 1996.     

Degrees-Of-Freedom in Multi-Cloud Based Sectored Cellular Networks

This paper investigates the achievable per-user degrees-of-freedom (DoF) in multi-cloud based sectored hexagonal cellular networks (M-CRAN) at uplink. The network consists of N base stations (BS) and K≤N base band unit pools (BBUP), which function as independent cloud centers. The communication between BSs and BBUPs occurs by means of finite-capacity fronthaul links of capacities CF=μF·12log(1+P) with P denoting transmit power. In the system model, BBUPs have limited processing capacity CBBU=μBBU·12log(1+P). We propose two different achievability schemes based on dividing the network into non-interfering parallelogram and hexagonal clusters, respectively. The minimum number of users in a cluster is determined by the ratio of BBUPs to BSs, r=K/N. Both of the parallelogram and hexagonal schemes are based on practically implementable beamforming and adapt the way of forming clusters to the sectorization of the cells. Proposed coding schemes improve the sum-rate over naive approaches that ignore cell sectorization, both at finite signal-to-noise ratio (SNR) and in the high-SNR limit. We derive a lower bound on per-user DoF which is a function of μBBU, μF, and r. We show that cut-set bound are attained for several cases, the achievability gap between lower and cut-set bounds decreases with the inverse of BBUP-BS ratio 1r for μF≤2M irrespective of μBBU, and that per-user DoF achieved through hexagonal clustering can not exceed the per-user DoF of parallelogram clustering for any value of μBBU and r as long as μF≤2M. Since the achievability gap decreases with inverse of the BBUP-BS ratio for small and moderate fronthaul capacities, the cut-set bound is almost achieved even for small cluster sizes for this range of fronthaul capacities. For higher fronthaul capacities, the achievability gap is not always tight but decreases with processing capacity. However, the cut-set bound, e.g., at 5M6, can be achieved with a moderate clustering size.     

Utility of the Pfitzinger Reaction in the Synthesis of Novel Quinoline Derivatives and Related Heterocycles

2‐(2‐Amino‐3,5‐dinitrophenyl)‐2‐oxoacetic acid ( 2 ) was obtained from hydrolysis of 5,7‐dinitroisatin ( 1 ) in alkaline media. A novel quinoxaline derivative ( 3 ) was synthesized from the reaction of the same compound ( 1 ) with o‐phenylenediamine. Reacting 2 with ethyl 3‐oxo‐3‐phenylpropanoate yields 6,8‐dinitro‐2‐phenylquinoline‐3,4‐dicarboxylic acid ( 4 ). Then, 4 was converted into new quinoline‐diacylchloride, quinoline‐ester, quinoline‐dicarboxamide, pyridazine, and pyrroledione derivatives ( 5 , 6a , 6b , 6c , 6d , 7a , 7b , 7c , 7d , 8 , 9 , 10a , 10b , 10c , 10d , 11a , 11b , 12 ) with SOCl₂, alcohols, amines, and hydrazines, respectively. The structures of synthesized compounds were clarified by ¹H NMR, ¹³C NMR, IR, mass and elemental analysis methods.     

Fixed points for mappings with a contractive iterate at each point

We generalize the results of Sehgal and Guseman for mappings on a complete metric space with a contractive iterate condition at each point.     

Synthesis of chiral chromenes from levoglucosenone

Levoglucosenone, an optically active α,β-unsaturated ketone available from cellulose, undergoes a stereoselective oxa-Michael-aldol domino reaction with 2-hydroxybenzaldehydes with the formation of optically active oxepino[4,5-b]chromen-1-ones. These compounds attacked by nucleophiles undergo recyclization to 4-substituted oxepino[3,4-b]chromen-11a-ols, while their oximes treated with SOCl₂ are converted to 3-cyano-2H-chromenes through the Beckmann fragmentation.     

Poly(pyrrole‐co‐pyrrole‐2‐carboxylic acid)/Pyruvate Oxidase Based Biosensor for Phosphate: Determination of the Potential,and Application in Streams

A biosensor based on conductive poly(pyrrole‐co‐pyrrole‐2‐carboxylic acid) [Poly(Py‐co‐PyCOOH)] copolymer film coated gold electrode was developed for the quantitative phosphate determination. Enzyme pyruvate oxidase was immobilized chemically via the functional carboxylated groups of the copolymer. The potential to be applied which is deficiency of phosphate biosensor studies for precise phosphate detection was clarified by using differential pulse voltammetry technique. Performance of the sensing ability of the biosensor was improved by optimizing cofactor/cosubstrate concentrations, polymeric film density and pH. The biosensor showed a linearity up to phosphate concentration of 5 mM, operational stability with a relative standard deviation (RSD) of 0.07 % (n=7) and accuracy of 101 % at ?0.15 V (vs. Ag/AgCl). Detection limit (LOD) and sensitivity were calculated to be 13.3 μM and 5.4 μA mM^?1 cm^?2, respectively by preserving 50 % of its initial response at the end of 30 days. It's performance was tested to determine phosphate concentrations in two streams of Zonguldak City in Turkey. Accuracy of phosphate measurement in stream water was found to be 91 %.